Power Platform Community Forum Thread Details

I am working on a cloud flow to parse a teams message when added to a chat. And the content is along the lines of "Can I get 20 tasks for unit 4 please". I set up variables to store the Task count and Unit number as a integer and string repsectively then the issue comes right after in the compose action. I think my expression is wrong but this is the error I'm getting - "Unable to process template language expressions in action 'ComposeTask' inputs at line '0' and column '0': 'The template language function 'indexOf' expects its first parameter to be of type string. The provided value is of type 'Null'. Please see https://aka.ms/logicexpressions#indexof for usage details.'." the expression i wrote is "

int(substring(triggerOutputs()?['body']?['content'], add(indexOf(triggerOutputs()?['body']?['content'], 'tasks'), -3), 2))" for task count and 
"substring(triggerOutputs()?['body']?['content'], add(indexOf(triggerOutputs()?['body']?['content'], 'unit'), 5), 2)" for unit number please help.