message: make string multi-line
diff: @@ -738,7 +738,10 @@ pub fn generate_emscripten_env(globals: &mut EmscriptenGlobals) -> ImportObject
  pub fn nullfunc(ctx: &mut Ctx, _x: u32) {
  use crate::process::abort_with_message;
  debug!("emscripten::nullfunc_i {}", _x);
  - abort_with_message(ctx, "Invalid function pointer called with signature 'i'. Perhaps this is an invalid value (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an incorrect type, which will fail? (it is worth building your source files with -Werror (warnings are errors), as warnings can indicate undefined behavior which can cause this)");
  + abort_with_message(ctx, "Invalid function pointer. Perhaps this is an invalid value \
  + (e.g. caused by calling a virtual method on a NULL pointer)? Or calling a function with an \
  + incorrect type, which will fail? (it is worth building your source files with -Werror (\
  + warnings are errors), as warnings can indicate undefined behavior which can cause this)");
  }
  /// The current version of this crate
  