Handle exceptions in CRubyWASI consistently with Opal

Author: eregon

app/ruby_engine.rb

@@ -9,6 +9,16 @@ def run(source)
     raise NotImplementedError
   end
 
+  def exception_to_string(err)
+    # Beautify the backtrace a little bit
+    backtrace = err.backtrace
+    backtrace = backtrace.select { |i| i.include? '<anonymous>' }
+    backtrace = backtrace.map { |i| i.gsub(/.*(<anonymous>)/, '\1') }
+    backtrace = ["(file)"] if backtrace.empty?
+    err.set_backtrace(backtrace)
+    err.full_message
+  end
+
   def run_with_writer(source, writer, &block)
     @writer = writer
     @dots = 0

app/ruby_engine/cruby_wasi.rb

@@ -106,7 +106,12 @@ def run(source)
 
       yield `vm.eval(source).toString()`
     rescue JS::Error => err
-      @writer.log_error(err)
+      raise err
+    end
+
+    def exception_to_string(err)
+      # "...: undefined method `reverse' for 40:Integer (NoMethodError)\n (Exception)\n"
+      super(err).sub(/\s+\(Exception\)\s*\z/, '')
     end
   end
 end

app/try_ruby.rb

@@ -431,13 +431,7 @@ def count_lines
 
   def log_error(err)
     unless err.is_a? String
-      # Beautify the backtrace a little bit
-      backtrace = err.backtrace
-      backtrace = backtrace.select { |i| i.include? '<anonymous>' }
-      backtrace = backtrace.map { |i| i.gsub(/.*(<anonymous>)/, '\1') }
-      backtrace = ["(file)"] if backtrace.empty?
-      err.set_backtrace(backtrace)
-      err = err.full_message
+      err = @engine.exception_to_string(err)
     end
 
     from = count_lines