different errors; readme edit

README.md

@@ -303,13 +303,13 @@ The config provides information for composing a set of transformers:
         migrations = "to/db/migrations"
 ```
 - `home` is the name of the package you are building the plugin for, in most cases this is github.com/vulcanize/vulcanizedb
-our `$GOPATH` but setting this to `true` overrides that. This needs to be set to `true` for the configs used in tests in order for them to work with Travis.
 - `name` is the name used for the plugin files (.so and .go)   
 - `save` indicates whether or not the user wants to save the .go file instead of removing it after .so compilation. Sometimes useful for debugging/trouble-shooting purposes.
 - `transformerNames` is the list of the names of the transformers we are composing together, so we know how to access their submaps in the exporter map
 - `exporter.<transformerName>`s are the sub-mappings containing config info for the transformers
     - `repository` is the path for the repository which contains the transformer and its `TransformerInitializer`
-    - `path` is the relative path from `repository` to the transformer's `TransformerInitializer` directory (initializer package)
+    - `path` is the relative path from `repository` to the transformer's `TransformerInitializer` directory (initializer package).
+        - Transformer repositories need to be cloned into the user's $GOPATH (`go get`)
     - `type` is the type of the transformer; indicating which type of watcher it works with (for now, there are only two options: `eth_event` and `eth_storage`)
         - `eth_storage` indicates the transformer works with the [storage watcher](https://github.com/vulcanize/maker-vulcanizedb/blob/compose_and_execute/libraries/shared/watcher/storage_watcher.go)
          that fetches state and storage diffs from an ETH node (instead of, for example, from IPFS)

pkg/plugin/builder/builder.go

@@ -60,15 +60,15 @@ func (b *builder) BuildPlugin() error {
 	}
 
 	// setup env to build plugin
-	err = b.setupBuildEnv()
+	setupErr := b.setupBuildEnv()
-	if err != nil {
+	if setupErr != nil {
-		return err
+		return setupErr
 	}
 
 	// Build the .go file into a .so plugin
-	err = exec.Command("go", "build", "-buildmode=plugin", "-o", soFile, b.goFile).Run()
+	execErr := exec.Command("go", "build", "-buildmode=plugin", "-o", soFile, b.goFile).Run()
-	if err != nil {
+	if execErr != nil {
-		return errors.New(fmt.Sprintf("unable to build .so file: %s", err.Error()))
+		return errors.New(fmt.Sprintf("unable to build .so file: %s", execErr.Error()))
 	}
 	return nil
 }
@@ -87,20 +87,20 @@ func (b *builder) setupBuildEnv() error {
 	// Import transformer dependencies so that we can build our plugin
 	for importPath := range repoPaths {
 		dst := filepath.Join(vendorPath, importPath)
-		src, err := helpers.CleanPath(filepath.Join("$GOPATH/src", importPath))
+		src, cleanErr := helpers.CleanPath(filepath.Join("$GOPATH/src", importPath))
-		if err != nil {
+		if cleanErr != nil {
-			return err
+			return cleanErr
 		}
 
-		err = helpers.CopyDir(src, dst, "vendor")
+		copyErr := helpers.CopyDir(src, dst, "vendor")
-		if err != nil {
+		if copyErr != nil {
-			return errors.New(fmt.Sprintf("unable to copy transformer dependency from %s to %s: %v", src, dst, err))
+			return errors.New(fmt.Sprintf("unable to copy transformer dependency from %s to %s: %v", src, dst, copyErr))
 		}
 
 		// Have to clear out the copied over vendor lib or plugin won't build (see issue above)
-		err = os.RemoveAll(filepath.Join(dst, "vendor"))
+		removeErr := os.RemoveAll(filepath.Join(dst, "vendor"))
-		if err != nil {
+		if removeErr != nil {
-			return err
+			return removeErr
 		}
 		// Keep track of this vendor directory to clear later
 		b.tmpVenDirs = append(b.tmpVenDirs, dst)

pkg/plugin/helpers/helpers.go

@@ -80,16 +80,19 @@ func CopyDir(src string, dst string, excludeRecursiveDir string) error {
 	var fds []os.FileInfo
 	var srcinfo os.FileInfo
 
-	if srcinfo, err = os.Stat(src); err != nil {
+	srcinfo, err = os.Stat(src)
+	if err != nil {
 		return err
 	}
 
-	if err = os.MkdirAll(dst, srcinfo.Mode()); err != nil {
+	mkErr := os.MkdirAll(dst, srcinfo.Mode())
-		return err
+	if mkErr != nil {
+		return mkErr
 	}
 
-	if fds, err = ioutil.ReadDir(src); err != nil {
+	fds, readErr := ioutil.ReadDir(src)
-		return err
+	if err != readErr {
+		return readErr
 	}
 	for _, fd := range fds {
 		srcfp := filepath.Join(src, fd.Name())
@@ -97,15 +100,15 @@ func CopyDir(src string, dst string, excludeRecursiveDir string) error {
 
 		if fd.IsDir() {
 			if fd.Name() != excludeRecursiveDir {
-				err = CopyDir(srcfp, dstfp, "")
+				dirErr := CopyDir(srcfp, dstfp, "")
-				if err != nil {
+				if dirErr != nil {
-					return err
+					return dirErr
 				}
 			}
 		} else {
-			err = CopyFile(srcfp, dstfp)
+			fileErr := CopyFile(srcfp, dstfp)
-			if err != nil {
+			if fileErr != nil {
-				return err
+				return fileErr
 			}
 		}
 	}