[GREENFOOT-574] Errors sometimes not shown

[reported by user Berthed Metz in email]

Reported sequence where error was not displayed:

• had correct method call to local method
• renamed method definition
• no error displayed at (now incorrect) method call

(Could not reproduce this. In my quick test this worked as intended. -mik)

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Issue metadata

• Issue type: Bug
• Priority: Medium
• Fix versions: 3.1.0