Improve exception for inconsistent mapping data

Author: rmaucher

java/org/apache/catalina/mapper/LocalStrings.properties

@@ -22,6 +22,7 @@ mapper.addHost.sameHost=Duplicate registration of the same host [{0}]. Ignored.
 mapper.addHost.success=Registered host [{0}]
 mapper.addHostAlias.sameHost=Duplicate registration of alias [{0}] for the same host [{1}]. Ignored.
 mapper.addHostAlias.success=Registered alias [{0}] for host [{1}]
+mapper.alreadyDone=Mapping was already done on this request on [{0}]
 mapper.duplicateHost=Duplicate Host [{0}]. The name is already used by Host [{1}]. This Host will be ignored.
 mapper.duplicateHostAlias=Duplicate host Alias [{0}] in Host [{1}]. The name is already used by Host [{2}]. This Alias will be ignored.
 mapper.findContext.noContext=No context found [{0}]

java/org/apache/catalina/mapper/Mapper.java

@@ -698,7 +698,7 @@ private void internalMap(CharChunk host, CharChunk uri, String version, MappingD
             // skipped all mapping work in this case. That behaviour has a risk
             // of returning an inconsistent result.
             // I do not see a valid use case for it.
-            throw new AssertionError();
+            throw new IllegalStateException(sm.getString("mapper.alreadyDone", mappingData));
         }
 
         // Virtual host mapping

java/org/apache/catalina/mapper/MappingData.java

@@ -57,4 +57,10 @@ public void recycle() {
         redirectPath.recycle();
         matchType = null;
     }
+
+    @Override
+    public final String toString() {
+        return "MappingData[" + host + ":" + context + ":" + wrapper + "]";
+    }
+
 }