translate-c: Fix macro define of float constant using scientific notation

Fixes compiler attempting to use null value when translating macro define of float constant using scientific notation with no decimal point

Author: riverbl

src/translate_c.zig

@@ -5602,16 +5602,18 @@ fn parseCNumLit(c: *Context, m: *MacroCtx) ParseError!Node {
         },
         .FloatLiteral => |suffix| {
             if (suffix != .none) lit_bytes = lit_bytes[0 .. lit_bytes.len - 1];
-            const dot_index = mem.indexOfScalar(u8, lit_bytes, '.').?;
-            if (dot_index == 0) {
-                lit_bytes = try std.fmt.allocPrint(c.arena, "0{s}", .{lit_bytes});
-            } else if (dot_index + 1 == lit_bytes.len or !std.ascii.isDigit(lit_bytes[dot_index + 1])) {
-                // If the literal lacks a digit after the `.`, we need to
-                // add one since `1.` or `1.e10` would be invalid syntax in Zig.
-                lit_bytes = try std.fmt.allocPrint(c.arena, "{s}0{s}", .{
-                    lit_bytes[0 .. dot_index + 1],
-                    lit_bytes[dot_index + 1 ..],
-                });
+
+            if (mem.indexOfScalar(u8, lit_bytes, '.')) |dot_index| {
+                if (dot_index == 0) {
+                    lit_bytes = try std.fmt.allocPrint(c.arena, "0{s}", .{lit_bytes});
+                } else if (dot_index + 1 == lit_bytes.len or !std.ascii.isDigit(lit_bytes[dot_index + 1])) {
+                    // If the literal lacks a digit after the `.`, we need to
+                    // add one since `1.` or `1.e10` would be invalid syntax in Zig.
+                    lit_bytes = try std.fmt.allocPrint(c.arena, "{s}0{s}", .{
+                        lit_bytes[0 .. dot_index + 1],
+                        lit_bytes[dot_index + 1 ..],
+                    });
+                }
             }
 
             if (suffix == .none)

test/translate_c.zig

@@ -1135,11 +1135,15 @@ pub fn addCases(cases: *tests.TranslateCContext) void {
         \\#define bar 16.e-2l
         \\#define FOO 0.12345
         \\#define BAR .12345
+        \\#define baz 1e1
+        \\#define BAZ 42e-3f
     , &[_][]const u8{
         "pub const foo = @as(f32, 3.14);",
         "pub const bar = @as(c_longdouble, 16.0e-2);",
         "pub const FOO = 0.12345;",
         "pub const BAR = 0.12345;",
+        "pub const baz = 1e1;",
+        "pub const BAZ = @as(f32, 42e-3);",
     });
 
     cases.add("comments",