[MINOR] fix in dropInvalidType

Logical error fix, break is replaced with continue.
diff --git a/src/main/java/org/apache/sysds/runtime/matrix/data/FrameBlock.java b/src/main/java/org/apache/sysds/runtime/matrix/data/FrameBlock.java
index d5ee5a7..175d400 100644
--- a/src/main/java/org/apache/sysds/runtime/matrix/data/FrameBlock.java
+++ b/src/main/java/org/apache/sysds/runtime/matrix/data/FrameBlock.java
@@ -1996,7 +1996,7 @@
 				type = "INT";
 			} else if (schemaCol.contains("STRING")){
 				// In case of String columns, don't do any verification or replacements.
-				break;
+				continue;
 			} else{
 				type = schemaCol;
 			}