Fix error handling in analysis.getError.

editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/AnalysisServer.java

Index: editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/AnalysisServer.java
diff --git a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/AnalysisServer.java b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/AnalysisServer.java
index 760295605111eb145ff58877b212dd17aa035128..978282eada71a0fdafc8314b2ecb842ec2adbb4b 100644
--- a/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/AnalysisServer.java
+++ b/editor/tools/plugins/com.google.dart.server/src/com/google/dart/server/AnalysisServer.java
@@ -51,6 +51,10 @@ public interface AnalysisServer {
    * information. Clients that can apply error information as it becomes available should use the
    * information provided by the 'analysis.errors' notification.
    *
+   * If a request is made for a file which does not exist, or which is not currently subject to
+   * analysis (e.g. because it is not associated with any analysis root specified to
+   * analysis.setAnalysisRoots), an error of type GET_ERRORS_INVALID_FILE will be generated.
+   *
    * @param file The file for which errors are being requested.
    */
   public void analysis_getErrors(String file, GetErrorsConsumer consumer);