Angular's NG8001 (build-time) and NG0304 (runtime) both mean the compiler can't resolve an element. Here's the exact cause and the real fix, standalone and NgModule.
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angular
NullInjectorError: No provider for HttpClient! (NG0201) means Angular's injector can't find a registered provider. Here's the exact fix for standalone apps, NgModules, and tests.
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angular
NG0203: inject() must be called from an injection context stops your app cold. Here's exactly why it happens and the three real fixes.
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angular