[Dana] Add erroneous program using byte variable as a condition

Author: kostis

dana/programs-erroneous/if_condition_byte.dana

@@ -0,0 +1,7 @@
+# Error: 'if' condition is not boolean (byte variable used as condition)
+
+def main
+    var b is byte
+    b := true
+    if b:
+        writeString: "erroneous"