Properly throw an error in compiler even when childCompilation is missing
Properly throw an error in compiler even when childCompilation is missing

For some errors, no other parameters to the function are even given,
only the error object in `err`.
SpaceK33z/html-webpack-plugin,ampedandwired/html-webpack-plugin,SimenB/html-webpack-plugin,SpaceK33z/html-webpack-plugin,jantimon/html-webpack-plugin,jantimon/html-webpack-plugin,SimenB/html-webpack-plugin,ampedandwired/html-webpack-plugin,dotch/html-webpack-plugin