Golang lib/pq: Runtime error when querying a database : I'm setting up a PostgreSQL database for my golang backend, but I'm getting this error when trying to read a table:

```
runtime error: invalid memory address or nil pointer dereference
/FwzFiles/go/src/runtime/panic.go:82 (0x4423b0)
        panicmem: panic(memoryError)
/FwzFiles/go/src/runtime/signal_unix.go:390 (0x4421df)
        sigpanic: panicmem()
/FwzFiles/go/src/database/sql/sql.go:1080 (0x4e59d9)
        (*DB).conn: db.mu.Lock()
/FwzFiles/go/src/database/sql/sql.go:1379 (0x4e7197)
        (*DB).prepare: dc, err := db.conn(ctx, strategy)
/FwzFiles/go/src/database/sql/sql.go:1352 (0x4e6f58)
        (*DB).PrepareContext: stmt, err = db.prepare(ctx, query, cachedOrNewConn)
/FwzFiles/go/src/database/sql/sql.go:1369 (0x9c8020)
        (*DB).Prepare: return db.PrepareContext(context.Background(), query)
/FwzFiles/go-projects/first-postgresql/main.go:62 (0x9c7fe2)
        AllEmployees: queryStmt, err := db.Prepare("SELECT * FROM employees ORDER BY id")
/home/f4ww4z/go/pkg/mod/github.com/gin-gonic/gin@v1.4.0/context.go:124 (0x991109)
        (*Context).Next: c.handlers[c.index](c)
/home/f4ww4z/go/pkg/mod/github.com/gin-gonic/gin@v1.4.0/recovery.go:83 (0x9a43d9)
        RecoveryWithWriter.func1: c.Next()
/home/f4ww4z/go/pkg/mod/github.com/gin-gonic/gin@v1.4.0/context.go:124 (0x991109)
        (*Context).Next: c.handlers[c.index](c)
/home/f4ww4z/go/pkg/mod/github.com/gin-gonic/gin@v1.4.0/logger.go:240 (0x9a3480)
        LoggerWithConfig.func1: c.Next()
/home/f4ww4z/go/pkg/mod/github.com/gin-gonic/gin@v1.4.0/context.go:124 (0x991109)
        (*Context).Next: c.handlers[c.index](c)
/home/f4ww4z/go/pkg/mod/github.com/gin-gonic/gin@v1.4.0/gin.go:389 (0x99a921)
        (*Engine).handleHTTPRequest: c.Next()
/home/f4ww4z/go/pkg/mod/github.com/gin-gonic/gin@v1.4.0/gin.go:351 (0x99a153)
        (*Engine).ServeHTTP: engine.handleHTTPRequest(c)
/FwzFiles/go/src/net/http/server.go:2774 (0x6ccd87)
        serverHandler.ServeHTTP: handler.ServeHTTP(rw, req)
/FwzFiles/go/src/net/http/server.go:1878 (0x6c8970)
        (*conn).serve: serverHandler{c.server}.ServeHTTP(w, w.req)
/FwzFiles/go/src/runtime/asm_amd64.s:1337 (0x459c50)
        goexit: BYTE    $0x90   // NOP

[GIN] 2019/08/17 - 16:25:18 | 500 |   23.812025ms |             ::1 | GET      /employees
```

Here's where the error is pointing at (`main.go:63`):
```
func AllEmployees(c *gin.Context) {
	// Query the Postgres employees table
	queryStmt, err := db.Prepare("SELECT * FROM employees ORDER BY id")
	rows, err := queryStmt.Query() // line 63
	if err != nil {
		panic(err)
	}
	defer rows.Close()

	// Extract the employees data from the query
	result := Employees{}
	for rows.Next() {
		employee := Employee{}
		err := rows.Scan(&employee.ID, &employee.Name, &employee.Salary, &employee.Age)
		if err != nil {
			panic(err)
		}
		result.Employees = append(result.Employees, employee)
	}

	c.JSON(http.StatusOK, gin.H{
		"employees": result,
	})
}
```

It should return 2 rows that I manually created on the `employees` table.
Note I'm successfully connected to the db, just that it errored when querying.

Can anyone help with this?