Flow Custom Funciton Not Returning String

Flow Custom Funciton Not Returning String

I have a simple custom function to return a string value in Flow. This works when I test the function in flow. When I run it in flow, it errors out (See below) 

Flow Output

  Value is empty and 'get' function cannot be applied at line number 4. Resolve the errors and try executing it again

Flow Input:

	"Owner": {
		"name": "nnnn nnnnn nnnnn",
		"id": 371195000000040030,
		"email": "xxxxxx@xxxxx.com"
string f_GetCrmOwnerEmail(map Owner)
v_Owner = Owner.getJson("Owner");
Owner_Email = v_Owner.get("email");
return Owner_Email.toString();
Any ideas? 


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