fix(variables): fix variable resolution error and start block outputs (#1847)

* Fix var resolution if block is not upstream

* Filter convo id from start block outputs if not set

* Lint

* Start block outputs

Author: Sg312

apps/sim/executor/execution/block-executor.ts

@@ -71,9 +71,21 @@ export class BlockExecutor {
 
     try {
       resolvedInputs = this.resolver.resolveInputs(ctx, node.id, block.config.params, block)
-    } finally {
+    } catch (error) {
       cleanupSelfReference?.()
+      return this.handleBlockError(
+        error,
+        ctx,
+        node,
+        block,
+        startTime,
+        blockLog,
+        resolvedInputs,
+        isSentinel,
+        'input_resolution'
+      )
     }
+    cleanupSelfReference?.()
 
     try {
       const output = handler.executeWithNode
@@ -120,58 +132,17 @@ export class BlockExecutor {
 
       return normalizedOutput
     } catch (error) {
-      const duration = Date.now() - startTime
-      const errorMessage = normalizeError(error)
-
-      if (blockLog) {
-        blockLog.endedAt = new Date().toISOString()
-        blockLog.durationMs = duration
-        blockLog.success = false
-        blockLog.error = errorMessage
-      }
-
-      const errorOutput: NormalizedBlockOutput = {
-        error: errorMessage,
-      }
-
-      this.state.setBlockOutput(node.id, errorOutput, duration)
-
-      logger.error('Block execution failed', {
-        blockId: node.id,
-        blockType: block.metadata?.id,
-        error: errorMessage,
-      })
-
-      if (!isSentinel) {
-        this.callOnBlockComplete(ctx, node, block, resolvedInputs, errorOutput, duration)
-      }
-
-      const hasErrorPort = this.hasErrorPortEdge(node)
-
-      if (hasErrorPort) {
-        logger.info('Block has error port - returning error output instead of throwing', {
-          blockId: node.id,
-          error: errorMessage,
-        })
-        return errorOutput
-      }
-
-      let errorToThrow: Error | string
-      if (error instanceof Error) {
-        errorToThrow = error
-      } else {
-        errorToThrow = errorMessage
-      }
-
-      throw buildBlockExecutionError({
+      return this.handleBlockError(
+        error,
+        ctx,
+        node,
         block,
-        error: errorToThrow,
-        context: ctx,
-        additionalInfo: {
-          nodeId: node.id,
-          executionTime: duration,
-        },
-      })
+        startTime,
+        blockLog,
+        resolvedInputs,
+        isSentinel,
+        'execution'
+      )
     }
   }
 
@@ -196,6 +167,68 @@ export class BlockExecutor {
     return this.blockHandlers.find((h) => h.canHandle(block))
   }
 
+  private handleBlockError(
+    error: unknown,
+    ctx: ExecutionContext,
+    node: DAGNode,
+    block: SerializedBlock,
+    startTime: number,
+    blockLog: BlockLog | undefined,
+    resolvedInputs: Record<string, any>,
+    isSentinel: boolean,
+    phase: 'input_resolution' | 'execution'
+  ): NormalizedBlockOutput {
+    const duration = Date.now() - startTime
+    const errorMessage = normalizeError(error)
+
+    if (blockLog) {
+      blockLog.endedAt = new Date().toISOString()
+      blockLog.durationMs = duration
+      blockLog.success = false
+      blockLog.error = errorMessage
+    }
+
+    const errorOutput: NormalizedBlockOutput = {
+      error: errorMessage,
+    }
+
+    this.state.setBlockOutput(node.id, errorOutput, duration)
+
+    logger.error(
+      phase === 'input_resolution' ? 'Failed to resolve block inputs' : 'Block execution failed',
+      {
+        blockId: node.id,
+        blockType: block.metadata?.id,
+        error: errorMessage,
+      }
+    )
+
+    if (!isSentinel) {
+      this.callOnBlockComplete(ctx, node, block, resolvedInputs, errorOutput, duration)
+    }
+
+    const hasErrorPort = this.hasErrorPortEdge(node)
+    if (hasErrorPort) {
+      logger.info('Block has error port - returning error output instead of throwing', {
+        blockId: node.id,
+        error: errorMessage,
+      })
+      return errorOutput
+    }
+
+    const errorToThrow = error instanceof Error ? error : new Error(errorMessage)
+
+    throw buildBlockExecutionError({
+      block,
+      error: errorToThrow,
+      context: ctx,
+      additionalInfo: {
+        nodeId: node.id,
+        executionTime: duration,
+      },
+    })
+  }
+
   private hasErrorPortEdge(node: DAGNode): boolean {
     for (const [_, edge] of node.outgoingEdges) {
       if (edge.sourceHandle === EDGE.ERROR) {

apps/sim/executor/utils/start-block.test.ts

@@ -71,8 +71,8 @@ describe('start-block utilities', () => {
     })
 
     expect(output.payload).toBe('value')
-    expect(output.input).toBe('')
-    expect(output.conversationId).toBe('')
+    expect(output.input).toBeUndefined()
+    expect(output.conversationId).toBeUndefined()
   })
 
   it('buildStartBlockOutput uses trigger schema for API triggers', () => {
@@ -101,8 +101,6 @@ describe('start-block utilities', () => {
         size: 42,
         type: 'text/plain',
         key: 'file-key',
-        uploadedAt: new Date().toISOString(),
-        expiresAt: new Date(Date.now() + 1000).toISOString(),
       },
     ]
 

apps/sim/executor/utils/start-block.ts

@@ -266,10 +266,25 @@ function buildUnifiedStartOutput(workflowInput: unknown): NormalizedBlockOutput
   }
 
   if (!Object.hasOwn(output, 'input')) {
-    output.input = ''
+    const fallbackInput =
+      isPlainObject(workflowInput) && typeof workflowInput.input !== 'undefined'
+        ? ensureString(workflowInput.input)
+        : ''
+    output.input = fallbackInput ? fallbackInput : undefined
+  } else if (typeof output.input === 'string' && output.input.length === 0) {
+    output.input = undefined
   }
+
   if (!Object.hasOwn(output, 'conversationId')) {
-    output.conversationId = ''
+    const conversationId =
+      isPlainObject(workflowInput) && workflowInput.conversationId
+        ? ensureString(workflowInput.conversationId)
+        : undefined
+    if (conversationId) {
+      output.conversationId = conversationId
+    }
+  } else if (typeof output.conversationId === 'string' && output.conversationId.length === 0) {
+    output.conversationId = undefined
   }
 
   return mergeFilesIntoOutput(output, workflowInput)
@@ -293,7 +308,11 @@ function buildChatOutput(workflowInput: unknown): NormalizedBlockOutput {
 
   const output: NormalizedBlockOutput = {
     input: ensureString(source?.input),
-    conversationId: ensureString(source?.conversationId),
+  }
+
+  const conversationId = ensureString(source?.conversationId)
+  if (conversationId) {
+    output.conversationId = conversationId
   }
 
   return mergeFilesIntoOutput(output, workflowInput)
@@ -319,7 +338,7 @@ function buildLegacyStarterOutput(
   }
 
   const conversationId = isPlainObject(workflowInput) ? workflowInput.conversationId : undefined
-  if (conversationId !== undefined) {
+  if (conversationId) {
     output.conversationId = ensureString(conversationId)
   }
 

apps/sim/executor/variables/resolvers/block.ts

@@ -43,8 +43,8 @@ export class BlockResolver implements Resolver {
 
     const output = this.getBlockOutput(blockId, context)
 
-    if (!output) {
-      throw new Error(`No state found for block "${blockName}"`)
+    if (output === undefined) {
+      return undefined
     }
     if (pathParts.length === 0) {
       return output