Fixed += not checking for String too long

src/EVAL.Z80

@@ -1,8 +1,8 @@
-	TITLE	BBC BASIC (C) R.T.RUSSELL 1981-2024
+	TITLE	BBC BASIC (C) R.T.RUSSELL 1981-2025
 ;
 ;BBC BASIC INTERPRETER - Z80 VERSION
 ;EVALUATE EXPRESSION MODULE - "EVAL"
-;(C) COPYRIGHT R.T.RUSSELL 1981-2024
+;(C) COPYRIGHT R.T.RUSSELL 1981-2025
 ;
 ;THE NAME BBC BASIC IS USED WITH THE PERMISSION
 ;OF THE BRITISH BROADCASTING CORPORATION AND IS
@@ -12,6 +12,7 @@
 ;VERSION 3.0, 08-03-1987
 ;VERSION 5.0, 31-05-2024
 ;VERSION 5.1, 28-12-2024
+;VERSION 5.2, 11-01-2025
 ;
 ;BINARY FLOATING POINT REPRESENTATION:
 ; 32 BIT SIGN-MAGNITUDE NORMALIZED MANTISSA
@@ -640,7 +641,7 @@ CONS2:	LD	A,(IY)
 	RET
 ;
 ARRAY:	LD	A,14		;'Bad use of array'
-	JP	ERROR
+	JR	ERROR0
 ;
 ; ARRLEN - Get start address and number of elements of an array
 ;   Inputs: HL addresses array descriptor
@@ -724,20 +725,21 @@ LOADS:	LD	DE,ACCS
 	EXX
 	OR	A
 	LD	C,A
-	LD	A,80H		;STRING MARKER
+REPDUN:	LD	A,80H		;STRING MARKER
 	RET	Z
 	LD	B,0
 	LDIR
 	RET
 ;
-LOADS2:	LD	A,(HL)
+LOADS2:	PUSH	IX
+	POP	HL
+LOADS3:	LD	A,(HL)
 	LD	(DE),A
 	INC	HL
 	CP	CR
-REPDUN:	LD	A,80H		;STRING MARKER
-	RET	Z
+	JR	Z,REPDUN
 	INC	E
-	JR	NZ,LOADS2
+	JR	NZ,LOADS3
 	RET			;RETURN NULL STRING
 ;
 ; Version 5 extensions:

src/EXEC.Z80

@@ -1,8 +1,8 @@
-		TITLE	BBC BASIC (C) R.T.RUSSELL 1981-2024
+		TITLE	BBC BASIC (C) R.T.RUSSELL 1981-2025
 ;
 ;BBC BASIC INTERPRETER - Z80 VERSION
 ;STATEMENT EXECUTION MODULE - "EXEC"
-;(C) COPYRIGHT R.T.RUSSELL 1981-2024
+;(C) COPYRIGHT R.T.RUSSELL 1981-2025
 ;
 ;THE NAME BBC BASIC IS USED WITH THE PERMISSION
 ;OF THE BRITISH BROADCASTING CORPORATION AND IS
@@ -12,6 +12,7 @@
 ;VERSION 3.1, 11-06-1987
 ;VERSION 5.0, 12-07-2024
 ;VERSION 5.1, 28-12-2024
+;VERSION 5.2, 11-01-2025
 ;
 	GLOBAL	XEQ
 	GLOBAL	RUN0
@@ -451,7 +452,6 @@ LET:	CALL	ASSIGN
 	JR	C,SYNTAX	;"Syntax error"
 	JP	P,LETARR	;Numeric array
 	JP	PE,LETARR	;String array
-	LD	A,D		;Type
 	PUSH	DE
 	PUSH	HL
 	CALL	EXPRS
@@ -2363,7 +2363,7 @@ MODIFY:	LD	A,E
 	CALL	FPP
 	POP	IX
 	POP	DE
-	JP	C,ERROR
+	JR	C,ERRORC
 STORE0:	LD	A,D		;Type
 STOREN:	CP	5
 	JR	Z,STORE5
@@ -2400,14 +2400,17 @@ MODIFS:	LD	A,L		;Operator
 	CP	'+'
 	LD	A,H		;Type
 	JR	NZ,STACCS
-	PUSH	IY
 	PUSH	IX
-	POP	IY
+	EX	(SP),IY
 	CALL	PUSHS
 	PUSH	IY
 	POP	IX
 	CALL	LOADS
 	POP	BC
+	LD	A,E
+	ADD	C
+	LD	A,19		;String too long
+ERRORC:	JR	C,ERROR6
 	LD	A,B		;Type
 	INC	C
 	DEC	C
@@ -2480,7 +2483,7 @@ CHECK:	PUSH	HL
 	POP	HL
 	RET	C
 	XOR	A
-	JP	ERROR		;"No room"
+ERROR6:	JP	ERROR		;"No room"
 ;
 STORS3:	LD	C,E
 	PUSH	IX