doc/conventions.txt: Exceptions

doc/conventions.txt

@@ -34,14 +34,6 @@ headers in src/ports/.
 Function naming:
 - Suffix _u: Unsafe, not included in public interface
 
-Do not use assert(); throw anonymous exceptions instead:
-- if(fail) throw Exception("Thing failed");
-
-In normal operation, zero exceptions should be thrown. Unless any potential bugs
-are occurring, you should be able to play the game fine if you set a breakpoint
-on a GCC Linux build to __cxa_throw, which will stop the program immediately
-when an exception occurs.
-
 Naming:
 - "type": Numeric id representing a type
 - "name": A string; generally works as an identifier but not necessarily
@@ -63,6 +55,20 @@ Ordering of #include directives:
 5) STL headers, <>
 6) System headers, <>
 
+Exceptions
+----------
+Do not use assert(); throw anonymous exceptions instead:
+- if(fail) throw Exception("Thing failed");
+
+In normal operation, zero exceptions should be thrown. Unless any potential bugs
+are occurring, you should be able to play the game fine if you set a breakpoint
+on a GCC Linux build to __cxa_throw, which will stop the program immediately
+when an exception occurs.
+
+Exceptions are allowed to occur when a resource has expired that the caller had
+to expect to still be valid in order to avoid some kind of ridiculous code
+structure.
+
 Non-exception throwing and exception-throwing methods
 -----------------------------------------------------
 - get_x: Returns nullptr or equivalent if not found