错误：遇到未定义的提供程序。 通常这意味着你有一个循环依赖（可能是由使用'桶' index.ts 文件引起的

Question

I dont know what causing this error. When I run ionic server command, It will display the following run time error.

Error: Encountered undefined provider! Usually this means you have a circular dependencies (might be caused by using 'barrel' index.ts files.
    at syntaxError (http://192.168.0.115:8100/build/vendor.js:93699:34)
    at http://192.168.0.115:8100/build/vendor.js:108838:40
    at Array.forEach (<anonymous>)
    at CompileMetadataResolver._getProvidersMetadata (http://192.168.0.115:8100/build/vendor.js:108823:19)
    at CompileMetadataResolver.getNgModuleMetadata (http://192.168.0.115:8100/build/vendor.js:108393:50)
    at JitCompiler._loadModules (http://192.168.0.115:8100/build/vendor.js:126717:87)
    at JitCompiler._compileModuleAndComponents (http://192.168.0.115:8100/build/vendor.js:126678:36)
    at JitCompiler.compileModuleAsync (http://192.168.0.115:8100/build/vendor.js:126594:37)
    at CompilerImpl.compileModuleAsync (http://192.168.0.115:8100/build/vendor.js:92535:49)
    at PlatformRef.bootstrapModule (http://192.168.0.115:8100/build/vendor.js:6107:25)
Ionic Framework: 3.9.2
Ionic App Scripts: 3.2.4
Angular Core: 5.0.0
Angular Compiler CLI: ^11.0.5
Node: 14.15.1
OS Platform: Windows 10
Navigator Platform: Win32
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36

Facing the error while running the project.

Answer 1

This error is thrown when a part of your code depends on second piece of code, that in turn depends upon the first piece. A simple example for this case would be if Service A calls a function of Service B but the function uses code in Service A. A cannot execute until B has finished executing, but B cannot execute unless A has finished executing. Hence the term, cyclic dependency.

The data you have provided is no where near sufficient to analyze the problem. Kindly share more.