Fix Loop block parameters (#1492)

skyvern-frontend/src/routes/workflows/editor/workflowEditorUtils.ts

@@ -368,14 +368,14 @@ function convertToNode(
       const loopVariableReference =
         block.loop_variable_reference !== null
           ? block.loop_variable_reference
-          : block.loop_over.key;
+          : block.loop_over?.key ?? "";
       return {
         ...identifiers,
         ...common,
         type: "loop",
         data: {
           ...commonData,
-          loopValue: block.loop_over.key,
+          loopValue: block.loop_over?.key ?? "",
           loopVariableReference: loopVariableReference,
         },
       };

skyvern/forge/sdk/workflow/models/yaml.py

@@ -142,8 +142,8 @@ class ForLoopBlockYAML(BlockYAML):
     # to infer the type of the parameter_type attribute.
     block_type: Literal[BlockType.FOR_LOOP] = BlockType.FOR_LOOP  # type: ignore
 
-    loop_over_parameter_key: str
     loop_blocks: list["BLOCK_YAML_SUBCLASSES"]
+    loop_over_parameter_key: str = ""
     loop_variable_reference: str | None = None