Fix empty array case

Author: janedbal

src/Internal/ArrayHelper.php

@@ -18,7 +18,8 @@ public static function unsetKeyAtPath(array &$array, array $path): void
 
 		if (count($tail) === 0) {
 			unset($array[$head]);
-		} else {
+
+		} elseif (isset($array[$head])) {
 			self::unsetKeyAtPath($array[$head], $tail);
 		}
 	}

tests/PHPStan/Internal/ArrayHelperTest.php

@@ -19,8 +19,7 @@ public function testUnsetKeyAtPath(): void
 			'dep1b' => null,
 		];
 
-		$path = ['dep1a', 'dep2a', 'dep3a'];
-		ArrayHelper::unsetKeyAtPath($array, $path);
+		ArrayHelper::unsetKeyAtPath($array, ['dep1a', 'dep2a', 'dep3a']);
 
 		$this->assertSame([
 			'dep1a' => [
@@ -29,6 +28,34 @@ public function testUnsetKeyAtPath(): void
 			],
 			'dep1b' => null,
 		], $array);
+
+		ArrayHelper::unsetKeyAtPath($array, ['dep1a', 'dep2a']);
+
+		$this->assertSame([
+			'dep1a' => [
+				'dep2b' => null,
+			],
+			'dep1b' => null,
+		], $array);
+
+		ArrayHelper::unsetKeyAtPath($array, ['dep1a']);
+
+		$this->assertSame([
+			'dep1b' => null,
+		], $array);
+
+		ArrayHelper::unsetKeyAtPath($array, ['dep1b']);
+
+		$this->assertSame([], $array);
+	}
+
+	public function testUnsetKeyAtPathEmpty(): void
+	{
+		$array = [];
+
+		ArrayHelper::unsetKeyAtPath($array, ['foo', 'bar']);
+
+		$this->assertSame([], $array);
 	}
 
 }