fix: move consumer validation to avoid unnecessary warnings

This commit moves the block that ensured the Provider was being used
inside the appropriate context into the component definition. This
removes the possibility of it logging a warning when ReactImgix
components are wrapped without the context component while also issuing
a warning when the provider is used without consumers.

src/HOCs/imgixProvider.jsx

@@ -9,11 +9,7 @@ const ImgixContext = createContext()
  * @returns Hook that gets context value from the nearest`ImgixProvider`.
  */
 function useImgixContext() {
-  const context = useContext(ImgixContext)
-  if (context === undefined) {
-    console.error("useImgixContext must be used within a ImgixProvider")
-  }
-  return context
+  return useContext(ImgixContext)
 }
 
 /**
@@ -27,6 +23,9 @@ function useImgixContext() {
 function ImgixProvider({children, ...reactImgixProps}) {
   const value = reactImgixProps
 
+  if ( children == null || children.length < 1) {
+    console.error("ImgixProvider must have at least one Imgix child component")
+  }
   return <ImgixContext.Provider value={value}>{children}</ImgixContext.Provider>
 }