improved error handling for illegal property values, e.g.

1. <property name="classLoader" value=""/>. Is it by accident or by
design that bean properties like this cannot be set because they aren't "simple" types?
2. <property name="tabWidth" value="eight"/>

src/checkstyle/com/puppycrawl/tools/checkstyle/api/AutomaticBean.java

@@ -182,6 +182,17 @@ public class AutomaticBean implements Configurable, Contextualizable
                     "cannot access " + key + " in "
                     + this.getClass().getName());
             }
+            catch (IllegalArgumentException e) {
+                throw new CheckstyleException(
+                    "illegal value '" + value + "' for property '" + key
+                    + "' of module " + aConfiguration.getName());
+            }
+            catch (ConversionException e) {
+                throw new CheckstyleException(
+                    "illegal value '" + value + "' for property '" + key
+                    + "' of module " + aConfiguration.getName());
+            }
+
         }
 
         finishLocalSetup();
@@ -222,6 +233,16 @@ public class AutomaticBean implements Configurable, Contextualizable
                     "cannot access " + key + " in "
                     + this.getClass().getName());
             }
+            catch (IllegalArgumentException e) {
+                throw new CheckstyleException(
+                    "illegal value '" + value + "' for property '" + key
+                    + "' of bean " + this.getClass().getName());
+            }
+            catch (ConversionException e) {
+                throw new CheckstyleException(
+                    "illegal value '" + value + "' for property '" + key
+                    + "' of bean " + this.getClass().getName());
+            }
         }
     }