Add an initial (non-working) modular exponentiation
diff --git a/src/data.c b/src/data.c
index 1b02e26..4aa1dd0 100644
--- a/src/data.c
+++ b/src/data.c
@@ -54,6 +54,9 @@
 	BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE, BC_ERR_IDX_PARSE,
 	BC_ERR_IDX_MATH, BC_ERR_IDX_MATH, BC_ERR_IDX_MATH, BC_ERR_IDX_MATH,
 	BC_ERR_IDX_MATH, BC_ERR_IDX_MATH,
+#ifdef DC_CONFIG
+	BC_ERR_IDX_MATH,
+#endif // DC_CONFIG
 	BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
 	BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
 	BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC, BC_ERR_IDX_EXEC,
@@ -94,6 +97,9 @@
 	"divide by zero",
 	"negative square root",
 	"bad number string",
+#ifdef DC_CONFIG
+	"modulus overflowed base",
+#endif // DC_CONFIG
 
 	"could not open file:",
 	"mismatched parameters",