Merge #11311

11311: Guard against empty inputs for objs expressions. r=RobbieMcKinstry a=RobbieMcKinstry

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# Description

`@dirien` raised an issue where tfgen would panic converting PCL under an edge case where an `ObjectExpression` had `nil` arguments. By introducing this guard, we skip annotating the the Object with the type provided by the schema the function in the schema has no args.

S/o to `@Zaid-Ajaj` for explaining this code to me and confirming the kill. I was lost without his aid! 

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Fixes #11305

## Checklist

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- [ ] I have added tests that prove my fix is effective or that my feature works
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- [x] I have run `make changelog` and committed the `changelog/pending/<file>` documenting my change
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Co-authored-by: Robbie McKinstry <robbie@pulumi.com>

changelog/pending/20221109--pkg--panic-in-codegen-obj-expressions.yaml

@@ -0,0 +1,4 @@
+changes:
+- type: fix
+  scope: pkg
+  description: Fix a panic in codegen for an edge case involving object expressions without corresponding function arguments.

pkg/codegen/pcl/invoke.go

@@ -150,7 +150,9 @@ func (b *binder) bindInvokeSignature(args []model.Expression) (model.StaticFunct
 
 	// annotate the input args on the expression with the input type of the function
 	if argsObject, isObjectExpression := args[1].(*model.ObjectConsExpression); isObjectExpression {
-		annotateObjectProperties(argsObject.Type(), fn.Inputs)
+		if fn.Inputs != nil {
+			annotateObjectProperties(argsObject.Type(), fn.Inputs)
+		}
 	}
 
 	return sig, nil