Prefer compile-time checking over run-time checking

doc/developer-notes.md

@@ -37,6 +37,7 @@ code.
 
 - **Miscellaneous**
   - `++i` is preferred over `i++`.
+  - `static_assert` is preferred over `assert` where possible. Generally; compile-time checking is preferred over run-time checking.
 
 Block style example:
 ```c++

src/arith_uint256.h

@@ -250,7 +250,7 @@ public:
 
     uint64_t GetLow64() const
     {
-        assert(WIDTH >= 2);
+        static_assert(WIDTH >= 2, "Assertion WIDTH >= 2 failed (WIDTH = BITS / 32). BITS is a template parameter.");
         return pn[0] | (uint64_t)pn[1] << 32;
     }
 };