improve error handling

src/de/inetsoftware/jwebassembly/WasmException.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017 - 2018 Volker Berlin (i-net software)
+ * Copyright 2017 - 2019 Volker Berlin (i-net software)
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -71,6 +71,19 @@ public class WasmException extends RuntimeException {
         lineNumber = -1;
     }
 
+    /**
+     * Create a new instance with a cause.
+     * 
+     * @param message
+     *            the detail message
+     * @param cause
+     *            the cause
+     */
+    private WasmException( String message, Throwable cause ) {
+        super( message, cause );
+        lineNumber = -1;
+    }
+
     /**
      * Create a wrapped exception needed.
      * 
@@ -125,6 +138,22 @@ public class WasmException extends RuntimeException {
         return new WasmException( cause );
     }
 
+    /**
+     * Create a wrapped exception needed with an additional message.
+     * 
+     * @param cause
+     *            the wrapped cause
+     * @param message
+     *            the message
+     * @return a new instance
+     */
+    public static WasmException create( String message, Throwable cause ) {
+        if( cause instanceof WasmException ) {
+            return (WasmException)cause;
+        }
+        return new WasmException( message, cause );
+    }
+
     /**
      * Get the line number in Java code on which the error occurred.
      * 

src/de/inetsoftware/jwebassembly/binary/BinaryModuleWriter.java

@@ -29,6 +29,7 @@ import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 
 import de.inetsoftware.jwebassembly.JWebAssembly;
+import de.inetsoftware.jwebassembly.WasmException;
 import de.inetsoftware.jwebassembly.module.FunctionName;
 import de.inetsoftware.jwebassembly.module.ModuleWriter;
 import de.inetsoftware.jwebassembly.module.TypeManager.StructType;
@@ -292,9 +293,14 @@ public class BinaryModuleWriter extends ModuleWriter implements InstructionOpcod
         int start = wasm.size();
         WasmOutputStream stream = new WasmOutputStream();
         stream.writeVaruint32( size );
-        for( Function func : functions.values() ) {
+        for( Entry<String, Function> entry : functions.entrySet() ) {
-            func.addCodeOffset( start + stream.size() );
+            try {
-            func.functionsStream.writeTo( stream );
+                Function func = entry.getValue();
+                func.addCodeOffset( start + stream.size() );
+                func.functionsStream.writeTo( stream );
+            } catch( RuntimeException ex ) {
+                throw WasmException.create( entry.getKey(), ex );
+            }
         }
         wasm.writeSection( SectionType.Code, stream );