fox32: Introduce better error handling

Instead of panicing, we now just print an error and exit in some
situations where a panic is too verbose. Maybe we should just change
the panic handler instead though?

src/main.rs

@@ -13,7 +13,7 @@ use mouse::Mouse;
 
 use std::env;
 use std::fs::{File, read};
-//use std::process::exit;
+use std::process::exit;
 use std::sync::{Arc, mpsc, Mutex};
 use std::thread;
 
@@ -47,11 +47,20 @@ fn read_rom() -> Vec<u8> {
     read("fox32.rom").unwrap_or_else(|_| {
         println!("fox32.rom not found, attempting to open ../fox32rom/fox32.rom instead");
         read("../fox32rom/fox32.rom").unwrap_or_else(|_| {
-            panic!("oh fuck");
+            error("fox32.rom not found!");
         })
     })
 }
 
+pub fn error(message: &str) -> ! {
+    println!("Error: {}", message);
+    exit(1);
+}
+
+pub fn warn(message: &str) {
+    println!("Warning: {}", message);
+}
+
 fn main() {
     let version_string = format!("fox32 {} ({})", env!("VERGEN_BUILD_SEMVER"), env!("VERGEN_GIT_SHA_SHORT"));
     println!("{}", version_string);

src/memory.rs

@@ -1,6 +1,6 @@
 // memory.rs
 
-use crate::Overlay;
+use crate::{Overlay, warn};
 
 use std::sync::{Arc, Mutex};
 
@@ -50,7 +50,7 @@ impl Memory {
         } else if address >= rom_bottom_address && address <= rom_top_address {
             self.rom[address - rom_bottom_address]
         } else {
-            println!("Warning: attempting to read unmapped memory address: {:#010X}", address);
+            warn(&format!("attempting to read unmapped memory address: {:#010X}", address));
             0
         }
     }
@@ -82,9 +82,9 @@ impl Memory {
             let mut shared_memory_lock = self.shared_memory.lock().unwrap();
             shared_memory_lock[address - shared_bottom_address] = byte;
         } else if address >= rom_bottom_address && address <= rom_top_address {
-            println!("Warning: attempting to write to ROM address: {:#010X}", address);
+            warn(&format!("attempting to write to ROM address: {:#010X}", address));
         } else {
-            println!("Warning: attempting to write to unmapped memory address: {:#010X}", address);
+            warn(&format!("attempting to write to unmapped memory address: {:#010X}", address));
         }
     }
     pub fn write_16(&mut self, address: u32, half: u16) {