ngc can now validate metadata before emitting to verify it doesn't
contain an error symbol that will result in a runtime error if
it is used by the StaticReflector.
To enable this add the section,
"angularCompilerOptions": {
"strictMetadataEmit": true
}
to the top level of the tsconfig.json file passed to ngc.
Enabled metadata validation for packages that are intended to be
used statically.
This lets users continue using runtime-sideeffect Decorators if they choose,
only down-leveling the marked ones to Annotations.
Also remove the "skipTemplateCodegen" option, which is no longer needed
since Angular compiles with tsc-wrapped rather than ngc. The former doesn't
include any codegen.