Improve the error message for toolchain selection when the default platform is not present.

PiperOrigin-RevId: 169387061

src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java

diff --git a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
index fb18457..ff5dc00 100644
--- a/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
+++ b/src/main/java/com/google/devtools/build/lib/skyframe/SkyframeBuildView.java
@@ -296,7 +296,11 @@
       if (cause instanceof ActionConflictException) {
         ((ActionConflictException) cause).reportTo(eventHandler);
       }
-      throw new ViewCreationFailedException(errorMsg);
+      if (errorInfo.getException() != null) {
+        throw new ViewCreationFailedException(errorMsg, errorInfo.getException());
+      } else {
+        throw new ViewCreationFailedException(errorMsg);
+      }
     }
 
     boolean hasLoadingError = false;