csv: fix last-field-empty error

vlib/encoding/csv/reader.v

@@ -129,7 +129,9 @@ fn (r mut Reader) read_record() ?[]string {
 		// quoted
 		else {
 			line = line[1..]
-			if j := line.index('"') {
+			j := line.index('"') or {
+				break
+			}
 			if j+1 == line.len {
 				// last record
 				fields << line[..j]
@@ -141,7 +143,6 @@ fn (r mut Reader) read_record() ?[]string {
 				line = line[j..]
 				continue
 			}
-			}
 			line = line[1..]
 		}
 		if i <= -1 && fields.len == 0 {

vlib/encoding/csv/reader_test.v

@@ -120,3 +120,30 @@ fn test_no_line_ending() {
 
 	assert row_count == 2
 }
+
+fn test_last_field_empty() {
+	data := '"name","description","value"\n"one","first","1"\n"two","second",\n'
+	mut csv_reader := csv.new_reader(data)
+
+	mut row_count := 0
+	for {
+    	row := csv_reader.read() or {
+        	break
+    	}
+    	row_count++
+		if row_count == 1 {
+			assert row[0] == 'name'
+			assert row[1] == 'description'
+			assert row[2] == 'value'
+		}
+		if row_count == 2 {
+			assert row[0] == 'one'
+			assert row[1] == 'first'
+			assert row[2] == '1'
+		}
+		if row_count == 3 {
+			assert row[0] == 'two'
+			assert row[1] == 'second'
+		}
+	}
+}