explained more errors in docs

git-svn-id: https://svn.code.sf.net/p/acme-crossass/code-0/trunk@260 4df02467-bbd4-4a76-a152-e7ce94205b78

docs/Errors.txt

@@ -255,6 +255,10 @@ File name quotes not found ("" or <>).
     File names have to be given in quotes. Either "" quoting for files
     located in the current directory or <> quoting for library files.
 
+Force bits can only be given to numbers.
+    You tried to give a force bit to a symbol and then assign a string
+    or list to it.
+
 Found '}' instead of end-of-file.
     ACME encountered a '}' character when it expected the file to end
     instead (because no blocks were open).
@@ -513,6 +517,9 @@ ArgStackNotEmpty
 ExtendingListWithItself
     There were multiple references to the same list.
 
+ForceBitZero
+    The function to handle force bits was called without a force bit.
+
 IllegalBlockTerminator
     A RAM block (macro or loop) was terminated incorrectly.
 
@@ -539,6 +546,10 @@ IllegalSymbolNameLength
 NotEnoughArgs
     There was not enough data for a dyadic operator to work on.
 
+NullTypeObject
+    A symbol is used that does not have a type (number/list/string)
+    associated with it.
+
 OperatorIsNotDyadic
 OperatorIsNotMonadic
     A function was passed the wrong type of operator.

src/symbol.c

@@ -175,12 +175,12 @@ void symbol_set_object(struct symbol *symbol, struct object *new_value, bits pow
 void symbol_set_force_bit(struct symbol *symbol, bits force_bit)
 {
 	if (!force_bit)
-		Bug_found("ForceBitZero", 0);	// FIXME - add to docs!
+		Bug_found("ForceBitZero", 0);
 	if (symbol->object.type == NULL)
-		Bug_found("NullObject", 0);	// FIXME - add to docs!
+		Bug_found("NullTypeObject", 0);
 
 	if (symbol->object.type != &type_number) {
-		Throw_error("Force bits can only be given to numbers.");	// FIXME - add to docs!
+		Throw_error("Force bits can only be given to numbers.");
 		return;
 	}