Cleanup for the static analyzer.

src/fmdb/FMDatabase.m

@@ -390,6 +390,11 @@ - (FMStatement*)cachedStatementForQuery:(NSString*)query {
 
 
 - (void)setCachedStatement:(FMStatement*)statement forQuery:(NSString*)query {
+    NSParameterAssert(query);
+    if (!query) {
+        NSLog(@"API misuse, -[FMDatabase setCachedStatement:forQuery:] query must not be nil");
+        return;
+    }
     
     query = [query copy]; // in case we got handed in a mutable string...
     [statement setQuery:query];