Fix incorrect logic in JSON number lexer

Detectable by gcc -Wlogical-op.

Add two regression test cases that would previously allow incorrect
values to pass.

src/backend/utils/adt/json.c

@@ -541,7 +541,7 @@ json_lex_number(JsonLexContext *lex, char *s)
 	if (*s == '.')
 	{
 		++s;
-		if (*s < '0' && *s > '9')
+		if (*s < '0' || *s > '9')
 			error = true;
 		else
 		{
@@ -558,7 +558,7 @@ json_lex_number(JsonLexContext *lex, char *s)
 		++s;
 		if (*s == '+' || *s == '-')
 			++s;
-		if (*s < '0' && *s > '9')
+		if (*s < '0' || *s > '9')
 			error = true;
 		else
 		{

src/test/regress/expected/json.out

@@ -113,6 +113,16 @@ ERROR:  invalid input syntax for type json
 LINE 1: SELECT '1f2'::json;
                ^
 DETAIL:  line 1: Token "1f2" is invalid.
+SELECT '0.x1'::json;			-- ERROR
+ERROR:  invalid input syntax for type json
+LINE 1: SELECT '0.x1'::json;
+               ^
+DETAIL:  line 1: Token "0.x1" is invalid.
+SELECT '1.3ex100'::json;		-- ERROR
+ERROR:  invalid input syntax for type json
+LINE 1: SELECT '1.3ex100'::json;
+               ^
+DETAIL:  line 1: Token "1.3ex100" is invalid.
 -- Arrays.
 SELECT '[]'::json;				-- OK
  json 

src/test/regress/sql/json.sql

@@ -22,6 +22,8 @@ SELECT '9223372036854775808'::json;	-- OK, even though it's too large for int8
 SELECT '1e100'::json;			-- OK
 SELECT '1.3e100'::json;			-- OK
 SELECT '1f2'::json;				-- ERROR
+SELECT '0.x1'::json;			-- ERROR
+SELECT '1.3ex100'::json;		-- ERROR
 
 -- Arrays.
 SELECT '[]'::json;				-- OK