flutter pub run build_runner watch —delete-conflicting-outputs

• extentions in VSCode:
• Snippet
• Freezed
• Injectable

Run the generator 
Use the [watch] flag to watch the files' system for edits and rebuild as necessary.

=> flutter packages pub run build_runner watch  
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if you want the generator to run one time and exits use

=> flutter packages pub run build_runner build

if there's problem
=>flutter packages pub run build_runner clean