Fix null pointer dereference in exception dump

Fix a couple of places in the Annotate function where null annotation
block pointers could be accessed. Should fix the Debugger crash from
this thread: https://www.riscosopen.org/forum/forums/4/topics/15014

Also trim some redundant code from the ExcPeekMem2 routine.

Version 2.07. Tagged as 'Debugger-2_07'

VersionASM

@@ -9,12 +9,12 @@
                         GBLS    Module_ApplicationDate
                         GBLS    Module_HelpVersion
                         GBLS    Module_ComponentName
-Module_MajorVersion     SETS    "2.06"
-Module_Version          SETA    206
+Module_MajorVersion     SETS    "2.07"
+Module_Version          SETA    207
 Module_MinorVersion     SETS    ""
-Module_Date             SETS    "28 Dec 2019"
-Module_ApplicationDate  SETS    "28-Dec-19"
+Module_Date             SETS    "05 Feb 2020"
+Module_ApplicationDate  SETS    "05-Feb-20"
 Module_ComponentName    SETS    "Debugger"
-Module_FullVersion      SETS    "2.06"
-Module_HelpVersion      SETS    "2.06 (28 Dec 2019)"
+Module_FullVersion      SETS    "2.07"
+Module_HelpVersion      SETS    "2.07 (05 Feb 2020)"
                         END

VersionNum

-/* (2.06)
+/* (2.07)
  *
  * This file is automatically maintained by srccommit, do not edit manually.
  *
  */
-#define Module_MajorVersion_CMHG        2.06
+#define Module_MajorVersion_CMHG        2.07
 #define Module_MinorVersion_CMHG        
-#define Module_Date_CMHG                28 Dec 2019
+#define Module_Date_CMHG                05 Feb 2020
 
-#define Module_MajorVersion             "2.06"
-#define Module_Version                  206
+#define Module_MajorVersion             "2.07"
+#define Module_Version                  207
 #define Module_MinorVersion             ""
-#define Module_Date                     "28 Dec 2019"
+#define Module_Date                     "05 Feb 2020"
 
-#define Module_ApplicationDate          "28-Dec-19"
+#define Module_ApplicationDate          "05-Feb-20"
 
 #define Module_ComponentName            "Debugger"
 
-#define Module_FullVersion              "2.06"
-#define Module_HelpVersion              "2.06 (28 Dec 2019)"
-#define Module_LibraryVersionInfo       "2:6"
+#define Module_FullVersion              "2.07"
+#define Module_HelpVersion              "2.07 (05 Feb 2020)"
+#define Module_LibraryVersionInfo       "2:7"

c/exc

@@ -841,7 +841,10 @@ static void Annotate(exc_context_t *ctx, uint32_t start, uint32_t end, eprocmode
 							{
 								/* Make a note of the address of the next frame */
 								excresult next_fp = ExcPeekMem(ctx, annotaddr);
-								block->next_fp = next_fp.val;
+								if (block)
+								{
+									block->next_fp = next_fp.val;
+								}
 								if (next_fp.ok)
 								{
 									if (!next_fp.val)
@@ -858,7 +861,7 @@ static void Annotate(exc_context_t *ctx, uint32_t start, uint32_t end, eprocmode
 											}
 										}
 									}
-									else
+									else if(block)
 									{
 										/* Forward-fill line flags */
 										for(int i=1;i<LINEBUFFER_SIZE;i++)

s/ExceptionDump

@@ -754,7 +754,6 @@ ExcWriteFile
         EXPORT ExcPeekMem2
 ExcPeekMem2    ROUT
         Entry
-        SUB     r12, sl, #:INDEX:CRelocOffset
         ; Check address directly
         BIC     a1, a2, #3
         ADD     a2, a1, #4
@@ -764,11 +763,6 @@ ExcPeekMem2    ROUT
         MOVCS   a1, #0
         MOVCS   a2, #0
         EXIT
-90
-        BIC     a3, a3, #3
-        LDR     a1, [a1, a3]
-        MOV     a2, #1
-        EXIT
 
 ; const char *ExcGetMsg(exc_context_t *ctx, exc_msg msg)
         EXPORT  ExcGetMsg